1. Field of the Invention
The present invention relates to a separation membrane having a good mass permeation property and a permeation selectivity, prepared from polyamide polymers containing 2,2'-bis(trifluoromethyl)biphenyl units and a process for separating gaseous mixtures using them. Technology which employs separation membranes for gaseous or liquid mixtures has been utilized in the various field. Such separation membranes have been used in a homogenous thin membrane or an asymmetric membrane type processed from polymeric or inorganic materials.
2. Description of the Prior Art
The polymeric separation membranes for separating fluids developed hitherto has been based on polymeric materials such as polyamides, polyimides, polysulphones, and the like. Polyamides are generally prepared by reacting diamines with dicarboxylic acids or dicarboxylic halides. While polyamides have superior mechanical and thermal properties, they also have low fluid permeability. In addition, the solvents in which polyamides can be dissolved are limited, and thus it is difficult to prepare the solutions for use in preparing the separation membranes. Improved gas separation polyamide membranes are reported in U.S. Pat. Nos. 3,899,309 and 5,073,176 incorporated herein with references, but there is still a need to improve a fluid permeability so as to enhance the efficiency of separation membranes.